The spleen a permanent placenta, the placenta a temporary spleen / by John Jackson.

  • Jackson, John, -approximately 1855.
Date:
1843
Catalogue details

Licence: Public Domain Mark

Credit: The spleen a permanent placenta, the placenta a temporary spleen / by John Jackson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    nary artery terminate in the capillaries of the lungs; and, again, as the blood is received from the portal plexuses by the hepatic veins, just as the blood is received from the pul- monary capillaries by the pulmonary veins,—it is obvious that the spleno-hepatic vein performs the duty of afferent vessel or artery, and also that the hepatic vascular system is a complete system. It remains then to be proved that the hepatic system is also an independent system,—that is, that it is not indebted to the left ventricle for the propul- sion of its blood; but that the spleno-hepatic vein is really and truly the propulsive agent or ventricle, as well as reci- pient cavity or auricle, and afferent vessel or artery. .25. The hepatic vascular system is not only regarded by most physiologists as a dependent system, or rather as a part of the general system, but it has been supposed by some to be dependent on the pulmonary as well as on the general system; that is, that the left ventricle and the right auricle manage to get the blood through the liver between them; the left ventricle as it were pushing the blood from behind, and the right auricle pulling at it in front. The opinion however almost universally entertained is, that it is the vis a tergo of the left ventricle which propels the portal blood through the liver: and this is the opinion which it is necessary to refute. It has been already shewn that there is no other course for the fluids received by the stomach to take, than through the gastric and duodenal veins into the spleno-hepatic vein: it follows, therefore, that not only is the portal blood a more or less diluted blood, but that much more diluted blood enters the heart by the hepatic veins, than there is arterial blood sujjplied to the digestive organs by the caliac and mesenteric arteries. This is the fact to which allusion has before been made as proving that the left ven- tricle is totally incapable of propelling the portal blood through the hepatic system; and a more positive and con- vincing proof than it is could not be adduced in refutation of an erroneous opinion; for it shews that if the left ven- tricle were the agent in the propulsion of the portal blood, it icould be necessary for it to be able by propelling a certain quantity of blood (say one ounce) into the cceliac atid mesenteric
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